The present invention relates to structures designed for absorbing body exudate. More particularly, the invention provides an improved sanitary absorbent article featuring an enhanced capability to protect the undergarment from wetting.
A sanitary napkin typically comprises an elongated main body that is intended to be placed in the crotch portion of the undergarment so it remains in contact with the perineal region of the wearer. The sanitary napkin includes a liquid-permeable cover layer located over an absorbent core that is designed to collect and store body exudate discharged by the user. Optionally, a transfer layer may be placed between the cover layer and the absorbent core. To prevent liquid collected in the absorbent core from soiling the undergarment of the wearer a liquid-impermeable barrier layer is located under the absorbent core.
Experimental procedures conducted on sanitary napkin designs have demonstrated that product failures can often be traced to the inability of the cover layer of the sanitary napkin, which is in contact with the perineal region of the wearer, to effectively capture on contact the discharge of body exudate. If liquid remains on the cover layer for an extended period of time droplets are likely to run off of the surface of the cover layer and leak past the edge of the sanitary napkin. The precise point of leakage depends primarily upon the posture of the wearer. For example, when a wearer lies horizontally in a supine position, the gravitational forces induce the liquid to travel longitudinally on the sanitary napkin and to accumulate on the rear longitudinal end portion. To avoid saturation and overflow leakage at that area, products with improved absorbency at the critical site have been developed during the past recent years. An example is the sanitary napkin available from Johnson and Johnson Inc. under the trade designation STAYFREE PRIMA Ultra Thin/Long Maxi. This product features a long body that progressively widens toward the rear so as to offer an increased liquid-acquisition surface area.
Alternatively, sanitary napkins designed primarily for daytime use have been found to leak mostly at the longitudinal sides of the napkin. This is primarily due to the normally erect or sitting positions of the wearer which causes the liquid to accumulate in the central area of the napkin which has a reduced width due to compressive forces exerted by the wearer""s legs. As a consequence, a much smaller surface area is available to the liquid for penetrating the absorbent structure.
In an attempt to reduce the possibility of undergarment or garment wetting resulting from side failures, several solutions have been proposed by the industry. One attempt to solve this problem is to provide the main body of the sanitary napkin with wings or flaps which extend from the longitudinal sides of the napkin and are folded about the edges of a crotch portion of a wearer""s undergarment to form upstanding walls which provide a shielding function. These flaps originate from the side edges of the main body and are provided with adhesive zones allowing the flaps to be secured against the outside surface of the undergarment. Thus, in the event that droplets of menstrual fluid leak past the side edges of the main body of the napkin, the undergarment will be protected from the liquid by virtue of the flaps.
This approach, however, presents a number of drawbacks. For example, the addition of side flaps to a sanitary napkin increases the manufacturing costs associated with the sanitary napkin. In addition, in an attempt to provide enhanced protection against side leakage, manufacturers have substantially increased the width of the flaps, measured along the length of the napkin, to provide wide flaps. Major difficulties observed with sanitary napkins provided with such wide flaps are the stresses created when fitting the flap about the curved edges of an undergarment and the inability of the flaps to conform well to the edges of the undergarment. Since the edges of the undergarment are outwardly curved from the narrow central crotch portion to become wider as the undergarment encircles the legs, wide flaps, when folded about the edges of the crotch portion of the undergarment will have a tendency to detach and/or form wrinkles which cause irritation and discomfort by chafing the inner thighs of the wearer and are also detrimental to the adhesive bond between the flaps and the undergarment, resulting in a further likelihood of detachment of the flaps from the undergarment. One possibility to solve this problem is to use a longitudinally extensible or elastic material to form wide flaps which are more comfortable to the shape of the undergarment edges.
Under a different approach the main body of the sanitary napkin is provided with flaps that are affixed to the barrier layer, i.e. on the garment facing side of the napkin, at a point located inwardly of the respective side edges of the sanitary napkin. The flaps may be adhered to the underside of the wearer""s undergarment or may be sufficiently long so they completely encircle the crotch portion of the undergarment and they are retained to one another in overlapping relationship. Since the flaps originate inwardly of the respective side edges, they have the effect of gathering the undergarment so that it remains inward of the longitudinal side edges of the main body. Thus, it is the body-facing side of the main absorbent body that provides the primary undergarment shielding function while the flaps positively prevent the edges of the undergarment from extending over the cover layer of the main body where they are subject to wetting. Examples of sanitary napkins constructed in accordance with this concept are described in U.S. Pat. No. 4,900,320 granted to McNeil-PPC on Feb. 13, 1990, which is incorporated herein by reference in its entirety.
The embodiments described in the U.S. Pat. No. 4,900,320 are, however, difficult to manufacture on high speed automated equipment because the flaps are formed separately of the main body and then affixed to the barrier layer of the main body in order to form the sanitary napkin. This requires a more complex manufacturing process that translates in higher production costs. Indeed, the industry has recognized that the most economical way of mass producing sanitary napkins is to form the flaps of the individual products integrally with the barrier layer, the cover layer or with both layers.
An object of the invention is to provide a sanitary napkin that is capable of protecting the undergarment of the wearer against wetting.
Another object of the invention is to provide a sanitary napkin that offers enhanced protection against undergarment wetting and which, at the same time, is easy to mass produce at low cost.
Yet, another object of the invention is to provide a method for manufacturing the aforementioned sanitary napkin.
As embodied and broadly described herein, the invention provides a sanitary absorbent article adapted to be worn in a crotch portion of an undergarment, comprising:
(A) a main body having opposed longitudinal side edges and a longitudinal centerline, said main body including: a body-facing fluid-permeable upper layer intended for placement against a perineal region of a wearer, a garment-facing fluid-impervious lower layer, and an absorbent layer between the upper layer and the lower layer; and
(B) a first panel and a second panel, each panel being integrally formed from the upper layer, the lower layer or a combination of both the upper layer and the lower layer, each panel having a proximal end adjacent to and extending from respective opposite longitudinal side edges of said main body and a distal end freely extending laterally from the proximal end of said panel, the proximal end and the distal end defining therebetween a body portion, the body portion further comprising a longitudinally extending folding axis which is substantially parallel to said longitudinal side edge, each panel being capable of being folded about said folding axis onto itself such that the distal end of the panel projects laterally inward towards the longitudinal centerline of said main body on a garment-facing side of the sanitary absorbent article, each panel further including:
(i) a juncture zone located within the body portion adjacent the proximal end of said panel, the juncture zone attaching a portion of said panel to the barrier layer inwardly from the longitudinal side edge of said main body, the juncture zone simultaneously defining a looping member and a freely extending flap
(ii) the looping member being adjacent to and substantially parallel with the longitudinal side edges of the main body and being defined by a portion of the body portion of said panel between the proximal end and the juncture zone and including the folding axis therebetween, the looping member being substantially unitized;
(iii) each flap being defined by a portion of the body portion of said panel between the juncture zone and the distal end and being capable of being folded about a side edge of the crotch portion of the undergarment, each flap further including a first transverse end and a second transverse end, the second transverse end being opposite the first transverse end and defining therebetween a flap width in a direction substantially parallel to the longitudinal side edges of the main body,
(iv) each flap having means for holding at least a portion of one edge of the undergarment inwardly of said longitudinal side edge of the main body when the flap is in a folded condition about the side edge of the undergarment, wherein the juncture zone of the first panel is separated from the juncture zone of said second panel by a distance which defines an undergarment allowance and the undergarment allowance, as measured at the respective transverse ends of the flaps, gathers the edges of the undergarment inward toward the longitudinal centerline of the main body in an amount less than 25% of the original width of the undergarment.
As embodied and broadly described herein, the present invention provides a method of manufacturing a plurality of sanitary absorbent articles comprising the steps of:
providing a continuous web of fluid pervious material having a width defined between opposite longitudinal sides,
forming a plurality of discrete elongated absorbent structures defined by an outer periphery having an upper surface and a lower surface, opposite longitudinal sides and opposite transverse ends, the absorbent structure being formed from fibrous absorbent materials,
adhering the upper surface of the absorbent structures to the fluid pervious material such that each absorbent structure is in a longitudinally spaced apart position with respect to an adjacent absorbent structure,
providing a continuous web of a fluid impervious material having a width defined between opposite longitudinal sides, adhering the lower surface of the absorbent structures to the fluid impervious material,
sealing the fluid pervious material to the fluid impervious material around the outer periphery of each absorbent structure forming a flange seal,
cutting the upper and lower surfaces along their respective longitudinal sides to form a pair of opposite side panels continuous with either the upper surface, the lower surface or both the upper surface and the lower surface, the side panels projecting laterally outward from a central potion of the absorbent structure, each panel having a base portion and a flap portion, the base portion being longer than the flap portion in a direction substantially parallel to the longitudinal sides of the absorbent structure, each panel further including a proximal end that is adjacent the absorbent structure, a distal end remote from the absorbent structure and a continuous body portion between the proximal end and the distal end;
folding the distal end of each panel under the main body;
affixing the base portion of the panel to the main body at a zone of juncture which is adjacent the proximal end of the panel so the panel remains in a folded condition, wherein the distal end is allowed to freely extend laterally inward thereby defining a freely extending flap and the body portion is located inwardly of the respective longitudinal side edge,
cutting the upper and lower surfaces across their entire width to form a plurality of individual sanitary napkins.
In a most preferred embodiment, the sanitary absorbent article is a sanitary napkin designed for absorbing menstrual liquid. The sanitary napkin includes a main body for placement against the perineal region of the wearer a pair of first liquid barriers extending substantially along the entire longitudinal side edges of the main body, the first liquid side barriers being formed by the looping members and a pair of flaps projecting laterally from the garment facing side of the main body, inward from the longitudinal side edges, the flaps being adapted to encircle the crotch portion of the undergarment. The main body is a layered structure including an upper, liquid-permeable cover layer, an absorbent system underneath the cover layer and a liquid-impermeable barrier layer below the absorbent system. The cover and the barrier layers may be peripherally sealed to one another to completely enclose the absorbent system.
The absorbent structure is generally an absorbent pulp fluff material, and may optionally comprise a dual-layer structure, including a highly porous transfer layer on top of a sphagnum moss absorbent core. It will be appreciated, however, that different absorbent systems can be used without departing from the spirit of the invention.
The panels originate from a central portion of the longitudinal side edges of the main body. Each panel has a base portion located at a proximal end that is continuous with and adjacent to the respective side edge of the main body, and flap portion a distal end continuous with the proximal end and which extends laterally outward from the longitudinal sides of the absorbent article. The base portion has a length longer than the flap portion. The distal end of the panel is folded underneath the barrier layer, i.e. on the garment facing surface of the absorbent article, and the panel is affixed to the barrier layer along the base portion at a juncture zone which is adjacent to the proximal end and inward of the longitudinal sides of the absorbent article so it remains in a folded condition. The folded portion of the flap forms a looping member which, when affixed to the barrier adjacent the flange, forms a first liquid barrier along the longitudinal sides of the napkin. The distal end thus forms a flap which extends inwardly from the respective side edge toward the longitudinal centerline of the absorbent article and is affixed inwardly of the side edge. As a result, when the flaps are folded about the crotch portion of the undergarment, they maintain or gather the undergarment sufficiently so the portions of the side edges of the undergarment located in the central area of the main body (those portions of the side edges of the undergarment are most susceptible of being wetted if failure occurs) remain within a boundary defined by the longitudinal side edges of the absorbent article. Accordingly, the main body of the absorbent article provides the major shielding function and protects the undergarment from being wetted and soiled with menstrual liquid.
The portion of the panel between the proximal end and the juncture zone defines a looping member. In order to reduce the cost of manufacturing the article, the looping member may be substantially unitized. In this context the term xe2x80x9csubstantial unitizedxe2x80x9d is used to indicate that the layers forming the looping member and all other material contained therein are attached together over an appreciable portion thereof to form an integral whole. The presence of unattached or free-floating structures within the looping member would significantly increase the cost of manufacture of the article.
Another advantage of this sanitary napkin configuration is the ability of the longitudinal side portions of the main body to resist the tendency to slope downwardly due to tension imparted by the flaps. That is, since the body portion of each flap originates inwardly of the respective side edge of the absorbent article, any tension which arises when the flap is fastened to the undergarment, will act against the barrier layer inwardly of the side edge. As a consequence, the peripheral edge portions of the main body are less likely to slope downwardly by comparison to a design where the tension imparted by the flaps act solely on the side edges. As mentioned before, such downward sloping is undesirable because it permits liquid pooling on the cover layer to leak sideways under the effect of gravity.
As embodied and broadly described herein, the present invention further provides a sanitary napkin, comprising:
(A) a main body having opposed longitudinal side edges, said main body including:
(i) a liquid-permeable cover layer,
(ii) an absorbent layer underneath the liquid-permeable cover layer, and
(iii) a liquid-impervious barrier layer below the absorbent layer, the cover layer and barrier layer being sealed about a peripheral edge margin to enclose the absorbent layer;
(B) a longitudinally extending looping member extending laterally outward from each respective longitudinal side edge, each looping member integrally formed from either the cover layer, the barrier layer, or both the cover layer and the barrier layer, the looping member being formed by folding at least one of said layers around and affixing the layer to the barrier layer at a juncture zone located inwardly of the respective longitudinal side edge;
(C) a pair of flaps on opposite sides of said main body, said flaps integrally formed from the looping member, said flaps being affixed to the barrier layer inwardly of the respective longitudinal side edge of the main body and projecting laterally from said main body in a direction generally transverse to the longitudinal side edges, each of said flaps including:
(I) a distal end continuous with the respective juncture zone which attaches at least a portion of said flap to the barrier layer, the distal end being folded under the barrier layer and extending laterally inwardly in a direction away from the respective longitudinal side edge,
(ii) a body portion retained to the distal end, the body portion being capable of being folded about a crotch portion of an undergarment on which the sanitary napkin is placed.
As embodied and broadly described herein the present invention further provides a method of manufacturing a sanitary napkin having a fluid-permeable cover layer, a fluid-impervious barrier layer, an absorbent core between the cover layer and the barrier layer, and flaps affixed to the barrier layer, comprising the steps of:
(A) adhering a first surface of the absorbent core to a surface of the fluid-permeable cover layer wherein the cover layer has a width which is greater than the width of the absorbent core;
(B) adhering a second surface of the absorbent core to a surface of the fluid-impervious barrier layer, wherein the barrier layer has a width substantially equivalent to the width of the cover layer;
(C) sealing the cover layer to the barrier layer around a peripheral edge margin of the absorbent core to form a flange seal;
(D) cutting the cover layer and the barrier layer outward of the flange seal in a pattern which defines a main body of a sanitary napkin having a pair of laterally extending panels, one panel extending from each respective longitudinal side of the main body of the sanitary napkin, the panels being integrally formed from either the cover layer, the barrier layer or both the cover layer and the barrier layer, the panels having a proximal end adjacent each respective longitudinal side edge of the sanitary napkin and a distal end extending laterally outward from the respective longitudinal side edge of the sanitary napkin;
(E) folding the panels along a folding axis under the barrier layer; and
(F) affixing the panels to the barrier layer along a juncture zone which is inward of the longitudinal side edges and underneath the main body of the sanitary napkin such that the distal end of the panels extend laterally inward toward a longitudinal centerline of the sanitary napkin thereby defining a pair of freely extending flaps.